Etcm 12351 dolos governed map data source

[ladamesny]

Description

Implemented governed map dolos data source and tweaked the stake distribution code. Confirmed that governed map, bridge and stake distribution sources from dolos is working on the local environment.

Checklist

• Commit sequence broadly makes sense and commits have useful messages.
• The size limit of 400 LOC isn't needlessly exceeded
• The PR refers to a JIRA ticket (if one exists)
• New tests are added if needed and existing tests are updated.
• New code is documented and existing documentation is updated.
• Relevant logging and metrics added
• Any changes are noted in the changelog.md for affected crate
• Self-reviewed the diff